Abstract 196: Involvement of Peroxynitrite Formation in Angiotensin II Induced Changes in Na+K+ATPase Activity in HK2 Cells

Hypertension ◽  
2012 ◽  
Vol 60 (suppl_1) ◽  
Author(s):  
Arpan K Maiti ◽  
Mohammed T Islam ◽  
Ryosuke Satou ◽  
Dewan S Majid
Keyword(s):  
Angiotensin Ii ◽  
Colorimetric Assay ◽  
Renin Angiotensin System ◽  
Human Kidney ◽  
Protective Role ◽  
Renal Tubules ◽  
Proximal Tubule Cell ◽  
Wide Range ◽  
Induced Changes ◽  
Hk2 Cells

Angiotensin II (AngII) induces both superoxide (O 2 - ) and nitric oxide (NO) generation forming peroxynitrite (ONOO - ) in biological systems. To determine the role of ONOO - in AngII induced sodium excretory responses, we examined Na + K + ATPase (NKA) activity in cultured HK2 cells (human kidney proximal tubule cell line) incubated for 30 min with a wide range (10 pM to 200 μM) of AngII concentrations (conc) in the presence or absence of a ONOO - scavenger, mercapto-ethyl-guanadine (MEG; 200μM). Post incubation HK2 cellular membrane fractions were used for measurement of NKA activity via colorimetric assay capable of detecting inorganic phosphate (Pi). Baseline value of NKA activity in these HK2 cells was measured as 10.3 ±0.7 μmoles of Pi liberated/mg protein/hr (n=12). AngII exerts dose-dependent differential effects on NKA activity. Compared to the baseline value, NKA activity was increased at lower conc (13.7±1.3% at 10 pM to 19.6±1.5% at 100nM) and decreased at higher conc (-6.0±0.8% at 1 μM to -38±2.1% at 200 μM ) without any significant effect at 500 nM conc (-1.2±0.6%) of AngII. Interestingly, MEG treatment markedly attenuated these AngII induced changes in NKA activity, both at lower conc (activity increased only to 7.8±0.67% at 10 pM and to 8.9±0.57% at 100nM; an average reduction of 33.2±2.4% in stimulatory effects) and at higher conc (activity decreased to -3.0±0.7% at 1 μM and to -20±0.57% at 200 μM; an average reduction of 54.4±4.1% in inhibitory effects). Co-incubation with O 2 - scavenger, tempol (1 mM) or NO synthase inhibitor, nitro-L-arginine methyl ester (100 μM) did not alter these AngII induced responses in HK2 cells indicating that neither O 2 - , nor NO, was directly involved in mediating these responses. AT 1 receptor (AT 1 R) blocker, losartan (10μM) treatment prevented these AngII induced changes on NKA activity confirming the involvement of AT 1 R signaling in these responses. These findings demonstrate a direct contributory role for concomitant ONOO - generation in mediating AngII induced changes in NKA activity in the proximal tubular cells. These data also suggest a reno-protective role for ONOO - in minimizing sodium retaining action of AngII by the renal tubules, particularly in the conditions associated with enhanced renin-angiotensin system.

Altered balance of main vasopressor and vasodepressor systems in rats with genetic hypertension and hypertriglyceridaemia

2002 ◽  
Vol 102 (3) ◽  
pp. 269-277 ◽  
Author(s):  
Jaroslav KUNEŠ ◽  
Zdenka DOBEŠOVÁ ◽  
Josef ZICHA
Keyword(s):  
Renin Angiotensin System ◽  
No Synthase ◽  
Superoxide Anions ◽  
Angiotensin System ◽  
Genetic Hypertension ◽  
Wide Range ◽  
Sympathetic Nervous ◽  
Induced Changes ◽  
Precise Role

The precise role of nitric oxide (NO) in hypertension is still not fully understood, although this vasodilator system represents the main counterbalance of major pressor systems. The aim of our study was to determine the contributions of superoxide anions, the renin-angiotensin system (RAS), the sympathetic nervous system (SNS) and NO to the maintenance of blood pressure (BP) in Prague hereditary hypertriglyceridaemic (HTG) rats with genetic hypertension. Conscious chronically cannulated rats were subjected to the consecutive blockade of the RAS (losartan, 10mg/kg), the SNS (pentolinium, 5mg/kg) and NO synthase [Nω-nitro-l-arginine (l-NAME), 30mg/kg]. Some additional rats were pretreated with tempol (a membrane-permeable mimetic of superoxide dismutase). A subsequent genetic study in HTG×Lewis F2 hybrid rats (n = 284) was designed to reveal potential associations of particular BP components with baseline BP. The progenitor study indicated that BP elevation was more pronounced in male than female HTG rats (as compared with normotensive Lewis controls). Higher BP in HTG rats was due to the increased residual BP (measured after combined RAS and SNS blockade) and the augmentation of BP responses to tempol or losartan. In contrast, BP responses to pentolinium or l-NAME were similar in all experimental groups. It should, however, be noted that the baseline BP of progenitor animals was correlated positively with both residual BP and the magnitude of the BP response to pentolinium, but not with BP response to l-NAME. Similarly, the baseline BP of F2 hybrid rats was positively associated with residual BP, the BP response to pentolinium and the relative SNS contribution to BP maintenance [expressed as a percentage of baseline mean arterial pressure (MAP) values], as well as with the ratio of BP changes elicited by ganglion blockade and NO synthase inhibition (ΔMAPpentolinium/ΔMAPl-NAME ratio), reflecting the balance of main vasopressor and vasodepressor systems. Thus our studies, performed in progenitor and F2 hybrid rats, revealed that changes in BP induced by l-NAME do not keep pace with the progressive augmentation of pentolinium-induced changes in BP occurring over a wide range of increasing BP. The altered balance between enhanced SNS-dependent vasoconstriction and unchanged NO-dependent vasodilation (‘relative NO deficiency’ in rats with high BP) might result in BP elevation in this form of genetic hypertension.

scholarly journals Renoprotective impact of angiotensin 1-7: Is it certain?

2018 ◽  
Vol 8 (1) ◽  
pp. 1-1
Author(s):  
Mehdi Nematbakhsh
Keyword(s):  
Angiotensin Ii ◽  
Physiological Condition ◽  
Renin Angiotensin System ◽  
Short Review ◽  
Protective Role ◽  
Ang Ii ◽  
Angiotensin System ◽  
Normal Physiological Condition ◽  
Current Article

The two important arms of renin angiotensin system (RAS) are angiotensin II (Ang II) and angiotensin1-7 (Ang1-7). Both of these peptides are present in the kidney, while the renal hemodynamic responses to these peptides act differently in kidney circulation. For this short-review, we used a variety of sources including PubMed, Google Scholar, and Scopus. Although in normal physiological condition, Ang1-7 has been known as an inactive agent in the renal system, however in past years many experimental and clinical reports indicated the protective role of Ang1-7 in renal hemodynamics and functions under different circumstances. In the current article, the possible renoprotective role of Ang1-7 was briefly reviewed.

Expression of angiotensin II type 1 receptor-interacting molecule in normal human kidney and IgA nephropathy

2010 ◽  
Vol 299 (4) ◽  
pp. F720-F731 ◽  
Author(s):  
Shin-ichiro Masuda ◽  
Kouichi Tamura ◽  
Hiromichi Wakui ◽  
Akinobu Maeda ◽  
Toru Dejima ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Iga Nephropathy ◽  
Renin Angiotensin System ◽  
Human Kidney ◽  
Receptor Signaling ◽  
Angiotensin System ◽  
Biopsy Specimens ◽  
Normal Human Kidney ◽  
Normal Human

The intrarenal renin-angiotensin system plays a crucial role in the regulation of renal circulation and sodium reabsorption through the activation of vascular, glomerular, and tubular angiotensin II type 1 (AT1) receptor signaling. We previously cloned a molecule that specifically interacted with the murine AT1 receptor to inhibit AT1 receptor signaling, which we named ATRAP (for AT1 receptor-associated protein). Since murine ATRAP was shown to be highly expressed in the kidney, in the present study we investigated expression and distribution of human ATRAP in normal kidney and renal biopsy specimens from patients with IgA nephropathy. In the normal human kidney, both ATRAP mRNA and protein were widely and abundantly distributed along the renal tubules from Bowman's capsule to the medullary collecting ducts. In all renal tubular epithelial cells, the ATRAP protein colocalized with the AT1 receptor. In renal biopsy specimens with IgA nephropathy, a significant positive correlation between ATRAP and AT1 receptor gene expression was observed. There was also a positive relationship between tubulointerstitial ATRAP expression and the estimated glomerular filtration rate in patients with IgA nephropathy. Furthermore, we examined the function of the tubular AT1 receptor using an immortalized cell line of mouse distal convoluted tubule cells (mDCT) and found that overexpression of ATRAP by adenoviral gene transfer suppressed the angiotensin II-mediated increases in transforming growth factor-β production in mDCT cells. These findings suggest that ATRAP might play a role in balancing the renal renin-angiotensin system synergistically with the AT1 receptor by counterregulatory effects in IgA nephropathy and propose an antagonistic effect of tubular ATRAP on AT1 receptor signaling.

scholarly journals Human kidney-2 cells harbor functional dopamine D1 receptors that require Giα for Gq/11α signaling

2013 ◽  
Vol 305 (4) ◽  
pp. F560-F567 ◽  
Author(s):  
Indira D. Pokkunuri ◽  
Gaurav Chugh ◽  
Mohammad Asghar
Keyword(s):  
Angiotensin Ii ◽  
Pertussis Toxin ◽  
Human Kidney ◽  
D1 Receptor ◽  
Dependent Manner ◽  
Downstream Signaling ◽  
Chelerythrine Chloride ◽  
Q Protein ◽  
Hk2 Cells ◽  
Rubidium Transport

A recent study demonstrated that the dopamine D1 receptor (D1R) is nonfunctional in human kidney cells, HK2 cells, in terms of their inability to couple to G s protein in response to the D1R agonist fenoldopam. Since D1R also couples to G q protein, we tested whether D1R is functional in HK2 cells in terms of their ability to couple to G q and produce downstream signaling. For comparison, we also studied another receptor, angiotensin II type 1 receptor (AT1R) known to couple to G q. Protein kinase C (PKC) and 86rubidium transport activities were determined as surrogate downstream signaling markers. Fenoldopam and angiotensin II increased PKC activity, which decreased in the presence of respective receptor antagonists (SCH23390 for D1R; candesartan for AT1R), PKC (chelerythrine chloride) and G i protein (pertussis toxin) inhibitors and G q/11α siRNA. Furthermore, fenoldopam and angiotensin II increased 35S-GTPγS binding, an index of receptor-G protein coupling, which decreased with pertussis toxin and in G q/11α-depleted cells. Also, fenoldopam-mediated inhibition of 86rubidium transport (an index of Na-K-ATPase activity) was attenuated with SCH23390, chelerythrine chloride, pertussis toxin, and G q/11α siRNA. Moreover, fenoldopam caused a decrease in cytosolic and increase in membranous abundance of G q/11α. The immunoprecipitated levels of G q/11α in the membranes were greater in fenoldopam-treated cells, and G iα coimmunoprecipitated with G q/11α. Our results suggest that both D1R and AT1R are functional in HK2 cells, enabling G q-mediated downstream signaling in a G i dependent manner.

scholarly journals Angiotensin II disrupts the cytoskeletal architecture of human urine-derived podocytes and results in activation of the renin-angiotensin system

2021 ◽  
Author(s):  
Lars Erichsen ◽  
Martina Bohndorf ◽  
Md. Shaifur Rahman ◽  
Wasco Wruck ◽  
James Adjaye
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Disease Modeling ◽  
Renin Angiotensin System ◽  
Human Kidney ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Renal Progenitor Cells ◽  
Potential Applications ◽  
Unique Cell

AbstractHigh blood pressure is one of the major public health problems which causes severe disorders in several tissues including the human kidney. One of the most important signaling pathways associated with the regulation of blood pressure is the renin-angiotensin system (RAS), with its main mediator angiotensin II (ANGII). Elevated levels of circulating and intracellular ANGII and aldosterone lead to pro-fibrotic, -inflammatory and -hypertrophic milieu that causes remodelling and dysfunction in cardiovascular and renal tissues. Furthermore, ANGII has been recognized as major risk factor for the induction of apoptosis in podocytes, ultimately leading to chronic kidney disease (CDK).In the past, disease modeling of kidney-associated malignancies was extremely difficult, as the derivation of kidney originated cells is very challenging. Here we describe a differentiation protocol for reproducible differentiation of SIX2-positive urine derived renal progenitor cells (UdRPCs) into mature podocytes bearing typical foot processes. The UdRPCs-derived podocytes show the ability to execute Albumin endocytosis and the activation of the renin-angiotensin system by being responsive to ANGII stimulation. Our data reveals the ANGII dependent downregulation ofNPHS1andSYNPO, resulting in the disruption of the complex podocyte cytoskeletal architecture, as shown by immunofluorescence-based detection of α–ACTININ. In the present manuscript we confirm and propose UdRPCs as a unique cell type useful for studying nephrogenesis and associated diseases. Furthermore, the responsiveness of UdRPCs-derived podocytes to ANGII implies potential applications in nephrotoxicity studies and drug screening.

Abstract P171: Superoxide via Transcription Factor Sp3 Up-regulates Renal Angiotensin II Receptor Function

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Mohammad Saleem
Keyword(s):  
Oxidative Stress ◽  
Angiotensin Ii ◽  
Human Kidney ◽  
Receptor Function ◽  
Angiotensin Ii Receptor ◽  
Percent Change ◽  
Nuclear Levels ◽  
And Function ◽  
Hk2 Cells

Oxidative stress is linked to the up-regulation of angiotensin II type 1 receptor (AT1R) function and hypertension. Here we tested the mechanism of oxidative stress-associated up-regulation of AT1 receptor function in human kidney HK2 cells. Diethyldithiocarbamate (DETC), a superoxide dismutase inhibitor, and hydrogen peroxide (H 2 O 2 ) increased DHE and DCFHDA fluorescence respectively [DHE fluorescence (Control vs DETC vs DETC + tempol vs H 2 O 2 : 0.5397 ± 0.07057, 1.463 ± 0.1671, 0.2661 ± 0.01776, 0.6406 ± 0.04821); DCFH fluorescence (Control vs H 2 O 2 vs 3-AT vs DETC: 555.9 ± 21.22, 673.5 ± 37.05, 736.1 ± 33.79, 427.7 ± 22.17)]. DETC increased nuclear levels of Sp3 protein that were attenuated with tempol (Control vs DETC, vs DETC + tempol: 0.50 ± 0.08, 1.28 ± 0.21, 0.52 ± 0.12 densities). However, H 2 O 2 had no significant effect on nuclear Sp3 (Control vs H 2 O 2, vs H 2 O 2 + tempol: Sp3, 0.50 ± 0.08, 0.68 ± 0.14, 1.04 ± 0.30 densities). In transfection studies, Sp3 plasmid increased (Control vs Sp3: 0.1165 ± 0.01, 0.3810 ± 0.03, densities) while Sp3 siRNA decreased (Control siRNA vs Sp3 siRNA: 1.11 ± 0.25, 0.64 ± 0.06, densities) the levels of AT1R protein in cell lysate. DETC increased AT1R protein expression that was attenuated by tempol, measured by immunoblotting (Control vs DETC vs DETC + tempol: 0.3535 ± 0.99, 0.9975 ± 0.19, 0.3250 ± 0.02 densities). Furthermore, DETC increased cell membrane levels of AT1R protein as measured by biotinylation and immunoblotting. This effect was attenuated by tempol. (Control vs DETC vs DETC + tempol: 100 ± 0.0, 189.8 ± 0.34.60, 102.3 ± 10.77 densities, percent change). Moreover, DETC increased PKC activity in response to angiotensin II, an indicator of AT1R function. This effect was attenuated with candesartan and tempol. (Control vs Ang II vs DETC + AngII vs DETC + Cand + AngII vs DETC + tempol: 100.0 ± 0.0, 162.0 ± 12.97, 224.9 ± 52.97, 126.0 ± 6.133, 73.32 ± 35.01 percent change) These results suggest that superoxide but not H 2 O 2 increase nuclear Sp3 protein that up-regulates renal AT1R expression and function.

The standardized extract of Nigella sativa and its major ingredient, thymoquinone, ameliorates angiotensin II-induced hypertension in rats

2018 ◽  
Vol 30 (1) ◽  
pp. 51-58 ◽  
Author(s):  
Lili Enayatfard ◽  
Reza Mohebbati ◽  
Saeed Niazmand ◽  
Mahmoud Hosseini ◽  
Mohammad Naser Shafei
Keyword(s):  
Angiotensin Ii ◽  
Main Product ◽  
Nigella Sativa ◽  
Renin Angiotensin System ◽  
Cardiovascular Effects ◽  
Angiotensin System ◽  
Hydroalcoholic Extract ◽  
Induced Hypertension ◽  
Induced Changes ◽  
Higher Doses

Abstract Background This study investigated the effect of hydroalcoholic extract of Nigella sativa (N. sativa) and its active component, thymoquinone (TQ) on hypertension induced by angiotensin II (AngII), the main product of renin–angiotensin system (RAS). Methods Seven animal groups (n=7 for each group) were used as follows: (1) control, (2) AngII (300 ng/kg), (3) AngII+losartan (Los; 10 mg/kg), (4) TQ (40 mg/kg)+AngII, and (5–7) three doses of N. sativa (200, 400, and 600 mg/kg)+AngII. Los and AngII were injected intravenously; TQ and extracts were injected intraperitoneally. In TQ and N. sativa-treated groups, 30 min after injection of the extract and TQ, AngII was injected. Cardiovascular parameters were recorded by power lab system after cannulation of femoral artery. The maximum changes (∆) of systolic blood pressure (SBP), mean arterial pressure (MAP), and heart rate (HR) were calculated and used for statistical analysis. Results AngII significantly increased maximal ∆SBP, ∆MAP, and ∆HR compared with the control (p<0.001), and these effects significantly were blunted by Los. TQ and two higher doses (400 and 600 mg/kg) of N. sativa significantly could antagonize effect of AngII on ∆SBP, ∆MAP (p<0.05 to p<0.001). AngII-induced changes of HR are also significantly decreased by TQ and dose 600 mg/kg of extract (p<0.01 and p<0.05, respectively). Conclusions The N. sativa and its component TQ have the beneficial effect on hypertension probably due to attenuation cardiovascular effects of AngII.

Distribution of angiotensin II receptor subtypes in rat and human kidney

1992 ◽  
Vol 262 (2) ◽  
pp. F236-F240 ◽  
Author(s):  
L. A. Sechi ◽  
E. F. Grady ◽  
C. A. Griffin ◽  
J. E. Kalinyak ◽  
M. Schambelan
Keyword(s):  
Angiotensin Ii ◽  
Binding Affinity ◽  
Human Kidney ◽  
Angiotensin Ii Receptors ◽  
Receptor Subtypes ◽  
Renal Tubules ◽  
Physiological Effects ◽  
Angiotensin Ii Receptor ◽  
Angiotensin Ii Receptor Subtypes

Angiotensin II initiates a variety of physiological effects in the kidney by binding to high-affinity receptors on plasma membranes. Recently, two subtypes of angiotensin II receptors have been distinguished on the basis of differences in signal transduction mechanisms, binding affinity to agonists and antagonists, and inhibition of binding by dithiothreitol. To evaluate the density and distribution of these receptor subtypes in the kidney, we performed an in situ autoradiographic study on frozen tissue sections obtained from rat and human kidneys. Sections were incubated with 125I-[Sar1,Ile8]angiotensin II and binding specificity was verified by competition with unlabeled [Sar1]angiotensin II. Angiotensin II receptor subtypes were characterized by competition with the nonpeptide receptor antagonists, DuP 753 (type 1) and PD123177 (type 2). Both rat and human kidney exhibited a high concentration of angiotensin II receptors in glomeruli and in the longitudinal bands traversing the outer portion of the medulla, corresponding to the medullary vascular bundles. Binding affinity (Kd = 0.6 +/- 0.4 nM), determined in rat kidney, was similar to that reported previously in isolated glomeruli and membrane vesicles prepared from renal tubules. Angiotensin II binding was almost completely inhibited by DuP 753, whereas PD123177 had little effect. Thus the predominant angiotensin II receptor subtype in both rat and human kidney is type 1. The distribution of angiotensin II receptors correlates well with the intrarenal sites at which the peptide has its major physiological effects.

A Review of Angiotensin Receptor Blocker-based Therapies at all Levels of Cardiovascular Risk

2011 ◽  
Vol 7 (4) ◽  
pp. 254 ◽  
Author(s):  
Giuliano Tocci ◽  
Lorenzo Castello ◽  
Massimo Volpe ◽  
◽  
◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Ventricular Hypertrophy ◽  
Renin Angiotensin System ◽  
Left Ventricular ◽  
Clinical Settings ◽  
Angiotensin Ii Receptor ◽  
Angiotensin System ◽  
Receptor Blockers ◽  
Artery Disease

The renin–angiotensin system (RAS) has a key role in the maintenance of cardiovascular homeostasis, and water and electrolyte metabolism in healthy subjects, as well as in several diseases including hypertension, left ventricular hypertrophy and dysfunction, coronary artery disease, renal disease and congestive heart failure. These conditions are all characterised by abnormal production and activity of angiotensin II, which represents the final effector of the RAS. Over the last few decades, accumulating evidence has demonstrated that antihypertensive therapy based on angiotensin II receptor blockers (ARBs) has a major role in the selective antagonism of the main pathological activities of angiotensin II. Significant efforts have been made to demonstrate that blocking the angiotensin II receptor type 1 (AT1) subtype receptors through ARB-based therapy results in proven benefits in different clinical settings. In this review, we discuss the main benefits of antihypertensive strategies based on ARBs in terms of their efficacy, safety and tolerability.

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